The present invention relates generally to air intake systems and more particularly to a hydrocarbon trap for adsorbing hydrocarbons in the air intake systems.
Due to laws requiring the reduction of the levels of hydrocarbons that vehicles may emit into the atmosphere, it is necessary for automotive designers to include systems in vehicles to measure and control emissions. Hydrocarbons are released in a vehicle""s exhaust, as well as from the engine, even when it is not operating. Hydrocarbons remaining from engine reactions can leak out of the engine through the engine""s air intake.
The first step in reducing hydrocarbon emissions is to measure the level of hydrocarbons present in the engine system. Many methods have been utilized to measure the level of hydrocarbons in the exhaust. For example the hydrocarbon level in vehicle exhaust gas is measured by placing a hydrocarbon adsorbing material in the exhaust stream of the vehicle. The hydrocarbon adsorbing material is connected to a sensor. The sensor is connected to an on-board diagnostic system that monitors the exhaust emissions and notifies the operator when the hydrocarbon level exceeds a certain level. However, this method does not reduce the hydrocarbon emissions by any significant amount.
Apart from measuring the level of hydrocarbons in the exhaust, it is thus beneficial to reduce the level of hydrocarbons. One method of doing so is to absorb hydrocarbons from the exhaust flow via a filter-like device. A problem arises, however, wherein the adsorbing element eventually becomes saturated with hydrocarbons and is no longer able to function effectively. It would be beneficial to have a hydrocarbon-trapping device that would not have this limitation. Such an element could also be used to condition the air intake flow to increase engine capacity as well as for implementing a hydrocarbon-measuring feature.
Typically, the hydrocarbon-trapping device is formed of monolith carbon that is disposed in the air induction system of motor vehicles. One of the problems with such positioning of the hydrocarbon-trapping device in the air induction system is the risk of breakage due to vibrations, or due to throttle engine backfire. In addition to the loss of function of the hydrocarbon-trapping device, large pieces of carbon monolith may move towards the engine, thereby resulting in a premature failure of the engine of a motor vehicle.
Therefore, it is highly desirable to have a hydrocarbon-trapping device that substantially prevents carbon pieces from traveling to the engine. Additionally, it is also desirable to have a hydrocarbon-trapping device that enhances the hydrocarbon adsorbing.
In one aspect of the present invention, a hydrocarbon trap is provided capable of adsorbing and releasing hydrocarbons and is positioned in the air intake system of a vehicle, upstream from the engine and wholly in the airflow.
In another aspect of the present invention, hydrocarbon trap comprises a housing and hydrocarbon adsorbing material, inserted inside the holder. A screen is added to the hydrocarbon trap such that in the event of premature breakage of the hydrocarbon adsorbing material the carbon particles do not flow towards the engine. In yet another aspect of the present invention, the hydrocarbon trap is provided with two screens.
In another aspect of the present invention, a hydrocarbon trap comprises a housing defining a cylindrical body. A clamping ring is attachable to the body with the help of a locking mechanism.
In yet another aspect of the present invention, the hydrocarbon trap comprises a housing, a hydrocarbon adsorbing material and two screens for protecting the hydrocarbon adsorbing material from flowing to the engine. The housing is formed by joining two cylindrical bodies. The two screens are attached to the housing, such that one screen faces the engine and the other screen faces away from the engine.
Other aspects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings.